Abstract

The thermal dependence of the magnetic entropy change (ΔSM(T)) and refrigerant capacity (RC) of austenite in as-quenched ribbons of chemical compositionNi51.1Mn31.2In17.7 produced by melt spinning at a high cooling rate of 48 ms−1 is reported. The effect of annealing at 1073 K on the structure and the magnetic properties was studied. The as-quenched sample is a single-phase austenite that presents a B2 ordered structure. The annealing on the melt spun samples produced a L21-type ordered structure. Austenite is characterized by a broad ΔSM(T) curve that, for a field change of 5.0 T, exhibits a full-width at half-maximum δTFMHW of 107 K, a peak value of the magnetic entropy change ΔSMpeak of −3.1 Jkg−1 K−1, and RC = 345 Jkg−1. Although annealed samples show larger ΔSMpeak values the narrower ΔSM(T) curves leads to a reduction in RC. Thus, the as-quenched sample shows a higher efficiency for a refrigerant cycle.